Weather in the Lake Tahoe region can change very rapidly. Snow packs can accumulate in hours making roads and traffic difficult. Snow can be seen flying year round in the tahoe basin especially at higher altitudes.
Summer brings out the hot sun so be alert to fire danger as well as sunburn. In the tahoe basin you are at an altitude of 6,200 feet where the atmosphere is much thinner than at sea level. In addition to suncreen, I recommend a rash guard with a high SPF rating for swimming. And definately do not forget the hat.
Layers of clothing should be worn in both summer and winter. Summer days are hot in the sun and cool in the shade. Summer nights can be very cold. Winter is cold, but the sun can provide relief so that a light jacket during the day is all that is needed. It is not unusual to see people skiing with shorts and short sleeves when the sun comes out.
Lake Tahoe is known for its snow, but it enjoys and average of 300 days of sunshine per year. Snow falls at a very fast rate and accumulations are around 10 feet at the lake shore and 25 - 40 feet in the higher elevations. The surface temperature of Lake Tahoe is 40-50F degrees in winter and 65-70F in summer which makes for a cool dip in the summer sun.
While visiting the Lake Tahoe region, wildlife should be respected and you should be aware of how coyotes, bears and mountain lions interact with humans (watch your children closely). Birds and mammals of the tahoe region are very active and can be viewed around the area.
Besides weather, construction can affect your ability to make good time around the area. Summer construction and repairs are common so check ahead before you travel as traffic delays can put a dent in your holiday.
Interactive maps are available at California and Nevada Road Conditions web sites:
California requires chains on all vehicles while Nevada allows for either chains or snow tires. Tips on winter driving.
California has check points during snowfall on the major highways. At California check points, installers generally charge $20.00 to put on chains provided by you as they are not allowed to sell chains. It is advisable to carry chains with you at all times while driving during the winter in the Lake Tahoe area for both safety and avoiding fines.